1. Field of the Invention
The present invention relates to pumps, and more particularly to a unitized seal, impeller, thrust system for use in a pump.
2. Description of Related Art
Many of the appliances used in everyday homes such as dishwashers and laundry machines include water pumps that have a mechanical face seal assembly which consists of a seal head and seal seat portion, a pump impeller and a thrust bearing system. Each of these systems are used to provide the sealing, pumping and axial force absorbing functions of the water pump, respectfully. Each of the systems are tested, handled and installed as individual components or sub-assembly units during construction of the actual water pump.
Many prior art pumps have used some pre-assembly of the above mentioned components such as sealing the seal seat portion of the mechanical face seal assembly and a thrust disc of the thrust bearing system into the pump impeller so that unitized components may be handled and installed into a single unit. However, components such as the thrust button of the thrust bearing system and the seal head of the mechanical face seal assembly must still be handled and installed as separate entities into other components of the pump such as the pump cover or the pump housing. This installation leaves the precision bearings and the sealing components exposed to damage or contamination until the entire pump is assembled. This type of construction for the pumps also precludes any leakage testing of the entire mechanical face seal assembly until after assembling and welding the entire pump closed because the proper mating of the seal head and seal seat portions is only achieved after completing the pump assembly. Hence, if the mechanical face seal assembly is found to have a leak after pump assembly has occurred, because of damage or contamination of seal components, salvaging of these pump components is not possible without destroying the pump housing and pump cover which have been welded or secured together. Another problem with the current pumps is that the thrust bearing is immersed in the liquid being pumped which exposes the bearing to chemical attack and/or abrasive wear which contributes to premature thrust bearing system wear and failure. This catastrophic pump failure occurs because the pump impeller then runs directly against the plastic cover of the pump, creating frictional heat high enough to melt through the cover allowing the fluid being pumped to leak out of the pump into surrounding areas.
Therefore, there is a need in the art for a new combination of a mechanical face seal assembly, a pump impeller and a thrust bearing system that is a unitized unit such that the entire assembly may be leak tested prior to installation and handled and installed as a single unit. Furthermore, there is a need for a thrust bearing system which is not immersed in and which is sealed off from the fluid being pumped within the pump chamber.